AMS 5536 Hastelloy X Plate

AMS 5536 Hastelloy X Plate is the high-temperature nickel alloy that furnace builders and gas turbine shops order when the service is defined by heat rather than by acid. The alloy, UNS N06002, is a solid-solution-strengthened nickel-chromium-iron-molybdenum material that holds useful strength at temperatures where stainless steel has already lost most of its load-carrying capacity, and it keeps an oxidation-resistant surface film that does not spall under thermal cycling. It is specified for combustion chambers, furnace liners, heat-treat fixtures, and process piping components that run hot and stay in service for years. 

 

Hastelloy X sits in a different market position from the corrosion grades in the same family. Alloys like C276 and C22 are bought for chemical resistance at moderate temperatures; Hastelloy X is bought for high-temperature strength, oxidation resistance, and fabricability above roughly 650°C. It is the alloy of choice for jet engine combustion liners, industrial furnace radiant tubes and muffles, and petrochemical furnace internals, where the design question is not "what will corrode" but "what will still hold load and stay intact at 900°C after thousands of thermal cycles".

ASTM B435 Hastelloy X Standard Specification

Specification	ASTM B435 / ASME SB435
Thickness	Ranging from 0.3mm to 20mm
Length	2000 mm / 2440 mm / 2500 mm / 3000 mm / 6000 mm.
Width	1000mm / 1219mm /1250mm / 1500mm / 2000mm
Hardness	As per ASME A & NACE MR 175
Finish	Hot rolled plate (HR), Cold rolled sheet (CR)

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Chemical composition of Hastelloy X plate per ASTM B435

The heat-analysis limits below follow ASTM B435 for UNS N06002 plate, sheet, and strip. The balance element is nickel, and the combination of chromium, iron, and molybdenum gives the alloy its dual character of oxidation resistance and high-temperature strength.

 

Element	Composition limit, %
Ni	Balance (nominally 47)
Cr	20.5 - 23.0
Fe	17.0 - 20.0
Mo	8.0 - 10.0
Co	0.5 - 2.5
W	0.2 - 1.0
C	0.05 - 0.15
Mn	1.0 max
Si	1.0 max
Al	0.50 max
Ti	0.15 max
Cu	0.50 max
B	0.010 max
P	0.040 max
S	0.030 max

 

The chromium row at 20.5-23.0% is the oxidation resistance: it forms a stable, tightly adherent Cr2O3-rich scale that protects the base metal in oxidizing furnace atmospheres. The molybdenum row at 8.0-10.0% is the high-temperature strength: molybdenum solid-solution strengthens the nickel matrix and slows creep at elevated temperatures.

 

The iron content at 17.0-20.0% is unusually high for a nickel alloy, and it does two jobs at once - it reduces alloy cost while broadening the corrosion and oxidation envelope in mixed furnace atmospheres. The deliberate carbon range of 0.05-0.15% provides some carbide strengthening without embrittling the alloy, which is why Hastelloy X maintains ductility even after long exposure in the 650-900°C range.

 

Mechanical properties of Hastelloy X plate

ASTM B435 requires the following minimum tensile properties for UNS N06002 plate in the solution-annealed condition, which is the standard delivery condition:

 

Property	Minimum value (ASTM B435)
Tensile strength	690 MPa (100 ksi)
Yield strength, 0.2% offset	276 MPa (40 ksi)
Elongation in 2 in (50.8 mm)	30%

 

Typical annealed production values run higher than the specification minimums. United Performance Metals' published typical data for annealed Alloy X plate show approximately 720 MPa (104,500 psi) tensile, 324 MPa (47,000 psi) yield, and 46% elongation at room temperature.

 

What matters for the furnace designer is not the room-temperature row but the elevated-temperature behavior: at 649°C (1200°F) the typical tensile is still about 472 MPa, and at 816°C (1500°F) it is still about 252 MPa with 51% elongation. The alloy carries load well above the point where austenitic stainless steel has dropped to a fraction of its room-temperature strength.

 

Physical properties

The density of Hastelloy X is 8.22 g/cm³ (0.297 lb/in³). The melting range is approximately 1260-1355°C (2300-2470°F). The alloy is essentially non-magnetic, with a magnetic permeability below 1.002, which matters in applications near sensitive instrumentation. Its thermal conductivity rises with temperature from about 9.1 W/m·K at room temperature to about 25.0 W/m·K at 816°C, and its electrical resistivity is about 115.8 microhm-cm at room temperature.

 

Property	Value
Density	8.22 g/cm³
Melting range	1260 - 1355°C (approx.)
Magnetic permeability	< 1.002
Thermal conductivity, 21°C	9.1 W/m·K
Thermal conductivity, 816°C	25.0 W/m·K
Electrical resistivity, 21°C	115.8 μΩ·cm

 

Manufacturing standards and plate forms

Hastelloy X plate is manufactured and supplied against the following specifications:

 

• ASTM B435 / ASME SB-435 - plate, sheet, and strip of UNS N06002
• AMS 5536 - sheet, strip, and plate (the aerospace procurement standard)
• ASTM B572 - bar and rod of the same alloy
• ASTM B366 - wrought fittings for piping systems in the alloy

 

The plate is produced by hot rolling the forged slab, then solution annealing and rapid cooling to put all alloying elements into solid solution. The anneal temperature is typically in the range of 1177°C (2150°F) with rapid cooling, which produces the fine-grained, fully austenitic structure that gives the alloy its combination of strength and ductility. Hastelloy X is not hardenable by heat treatment; its strength comes entirely from solid-solution strengthening and work hardening, so cold rolling is the only route to higher strength tempers.

 

Available plate sizes and tolerances

Hastelloy X plate is supplied in the following standard envelope, with project-specific sizes available on request:

 

Parameter	Range
Thickness	0.5 mm to 75 mm (sheet from 0.5 mm, plate from 4.75 mm)
Width	1000 mm, 1219 mm (4 ft), 1500 mm, 2000 mm, 2500 mm
Length	2000 mm, 2438 mm (8 ft), 3000 mm, 6000 mm
Surface finish	Hot-rolled annealed, pickled, or abrasive-blasted
Edge	Sheared, plasma-cut, or machined as specified

 

The standard plate thickness tolerance for B435 material follows the ASTM A480 table for nickel alloy plate: for example, a 6 mm plate carries approximately a +/-0.40 mm thickness tolerance, and the tolerance widens with increasing thickness. Flatness is controlled within the specification, and for laser-cut or plasma-cut blanks the buyer should state the flatness requirement on the PO, because cutting introduces distortion that the plate mill does not correct.

 

High-temperature performance: what the furnace designer buys

The value of Hastelloy X plate is delivered in three service properties. First, oxidation resistance: the alloy is rated for continuous service in oxidizing atmospheres up to about 1204°C (2200°F), and it develops a tenacious oxide film that resists spalling under thermal cycling.

 

Second, high-temperature strength: the alloy maintains useful load capacity to about 816°C (1500°F), where its typical tensile remains above 250 MPa - roughly five times the strength of 316L at the same temperature. Third, resistance to carburization and nitriding: in furnace atmospheres that would carbonize or nitride stainless steel surfaces, Hastelloy X stays ductile and crack-free.

 

Duty	Hastelloy X behavior	Typical limit
Oxidizing atmosphere, continuous	Excellent, non-spalling scale	~1204°C
High-temperature load bearing	Good to 816°C, useful beyond	Strength falls off above 982°C
Carburizing atmospheres	Good resistance	Better than stainless grades
Nitriding atmospheres	Good resistance	Surface hardening limited
Reducing / neutral furnace gas	Good	Stable over the service range
Corrosive chemical service below 650°C	Moderate	Not the primary reason to buy X

 

This is the key selection distinction: if the service is a chemical acid attack below 650°C, a corrosion grade such as C276 or C22 is the correct alloy. If the service is heat - a furnace, a gas turbine, a pyrolysis unit - Hastelloy X is the alloy that the design engineer reaches for. The two families overlap only in a narrow band, and the specification should be made on the temperature profile of the duty, not on price.

 

Typical applications for Hastelloy X plate

Hastelloy X plate is specified for components that live at temperature:

 

• Gas turbine combustion chambers, transition pieces, and afterburner components
• Industrial furnace radiant tubes, muffles, retorts, and heat-treat baskets and fixtures
• Jet engine combustor liners and tailpipe assemblies (AMS 5536 procurement)
• Petrochemical furnace internals and pyrolysis heater components
• Chemical plant equipment operating in high-temperature oxidizing or reducing atmospheres
• Flash drier components and catalyst-grid support plates

 

Welding and fabrication

Hastelloy X is one of the most fabricable high-temperature nickel alloys. It welds readily by GTAW (TIG), GMAW (MIG), and resistance welding, using matching filler metal of the same chemistry. No preheat is required, and no post-weld heat treatment is required for most services, because the alloy's strength is not dependent on a heat-treatment response.

 

The alloy work-hardens during machining, so fabrication should use rigid setups, sharp tooling, and controlled cutting speeds; plasma cutting is commonly used for plate profiling, followed by grinding or machining of the cut edge where the weld joint requires it. After cutting, the oxide layer at the edge should be removed before welding to avoid inclusions in the weld.

 

Quality control and certification

Hastelloy X plate is supplied with the mill test certificate reporting heat chemistry, mechanical test results, and the examination performed. For AMS 5536 procurement, the certificate additionally confirms compliance with the aerospace specification requirements.

 

The standard examination package includes ultrasonic examination where the order requires it, and positive material identification (PMI) is recommended on receipt, because Hastelloy X is visually similar to other high-nickel alloys and the composition difference is not detectable by eye. Certificates are issued per EN 10204 3.1 or 3.2 as specified, and third-party inspection is arranged on request.

 

Hastelloy X plate is a specialized high-temperature product, and the buying decision rests on the service temperature and atmosphere, not on price alone. When the enquiry specifies UNS N06002, the plate should be ordered against ASTM B435 or AMS 5536 with the annealed condition stated, the thickness and flatness requirement given explicitly, and the certificate format confirmed with the project QA plan.

 

 

 

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